Crown Morphology Relationships among Alfalfa Plant Introductions and Cultivars

Abstract

The alfalfa (Medicago sativa L.) crown is an important morphological structure because of its association with regrowth, yield, and persistence. The objectives of this research were to evaluate variability for crown morphological traits among 1067 plant introductions (P.I.s) and 110 North American cultivars, to determine the association between crown morphological traits and germplasm sources, and to compare the association between crown morphological traits and fall dormancy classes for North American alfalfa cultivars. The P.I.s and the cultivars were grown in separate field studies at Rosemount, MN, during 1989 and 1990, respectively. Plots consisted of one 3.5‐m‐long row for P.I.s, and one 1.8‐m‐long row for cultivars. They were seeded in May and the plants were dug in October. Plants were individually evaluated for crown depth, crown width, number of crown stems, crown stem width, and number of crown buds. Variation was observed among both P.I.s and North American cultivars for all crown traits. Discriminant analysis of crown traits was effective at separating germplasm sources from diverse geographic origins. The crown traits of germplasm sources from less diverse origins appeared similar. Discriminant analysis of crown traits separated highly dormant (fall dormancy = 1) cultivars more effectively than semi‐dormant and non‐dormant cultivars. Only number of crown buds had a meaningful correlation (−) with fall growth. Variation observed for crown traits among alfalfa germplasm sources indicated that selection for specific crown modifications could be effective.